Flighty

[Luis Fok]

Indulging in flights, or wild and unrestrained sallies, of
imagination, humor, caprice, etc.; given to disordered fancies and
extravagant conduct; volatile; giddy; eccentric; slighty delirious.

[Sonia]

A [polite] [way] of describing someone who is [bat shit crazy]

[Dave Paprocki]

someone who [moves] from one person [to the] [next]

[Becky]

Fickle and irresponsible.

[Sommer]

The [nervous] need to change things [alot] or the opposite of [stable].

[Sonia]

(especially of a woman) not responsible and likely to change activities, jobs, boyfriends, etc. often: